The term human enhancement refers to a set of actual or proposed actions that aim to increase the potential of the human body, and even create new ones. Most of these actions are based on a reorientation of biomedical techniques used in medical practice, but now also appeal to converging technologies. This article distinguishes three uses of the English term, according to the meaning given to the adjective "human": improvement of human capacities, improvement of human nature, self-improvement. These layers of meaning stem from different contexts but all draw on longstanding currents of thought. It is this collusion of old ideas and new means that is expressed in the term human enhancement.